I'm trying to access this API, for a coding interview test (so I've masked the URLs), but I'm getting "HTTP/1.1 400 BAD_REQUEST Content-Length: 0 Connection: Close". I'm using the example URL and the hostname/headers they provided.

What could I be missing in my request that is causing this problem, short of the URL being wrong?

<?php
$url = "api-recruitment-test.com";
$ch = curl_init($url);

$api_headers = array(
    'Accept­Tenant: uk',
    'Accept­Language: en-GB',
    'Authorization: Basic VGVjaFRlc3RBUEk6dXNlcjI=',
    'Host: api-recruitment-test'
    );

curl_setopt($ch, CURLOPT_HEADER, TRUE);
curl_setopt($ch, CURLOPT_HTTPHEADER, $api_headers);
curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.2 (KHTML, like Gecko) Chrome/22.0.1216.0 Safari/537.2');

$data = curl_exec($ch);

$info = curl_getinfo($ch);
    echo '<pre>';
      print_r($info);
      echo '</pre>';

curl_close($ch);


//test the url connection
if (!$fp = fopen($url, 'r')) {
    trigger_error("Unable to open URL ($url)", E_USER_ERROR);
}

$json = file_get_contents($data);
$data = json_decode($json, TRUE);
print_r($data);


$meta = stream_get_meta_data($fp);
echo '<pre>';
var_dump($meta);
echo '</pre>';

fclose($fp);
?>